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      <title>1、js - 学习卡片</title>
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        <h1>1、js - 学习卡片</h1>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">理论</div>
          <div class="card-question">JavaScript的核心定义是什么？它有哪些主要特点？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">理论</div>
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            <div class="card-answer">JavaScript是基于对象和事件驱动的脚本语言，主要嵌入HTML在客户端动态操作网页元素。其主要特点包括：交互性（如表单校验、异步提交）、安全性（不可以直接访问本地硬盘）和跨平台性（由浏览器解析执行，与平台无关）。</div>
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          <div class="card-source">来源: 什么是javascript</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
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        <div class="card-face card-front">
          <div class="card-category">技术</div>
          <div class="card-question">文档中提到了JavaScript和Java的哪些关键区别？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">主要有两个区别：1. 执行方式不同，JavaScript由浏览器直接解析执行，而Java需要先编译成字节码文件再由JVM执行。2. 类型系统不同，JavaScript是弱类型语言（变量类型在执行时才确定），而Java是强类型语言（类型具有严格规范）。</div>
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          <div class="card-source">来源: Javascript vs Java</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">理论</div>
          <div class="card-question">一个完整的JavaScript实现由哪三个部分组成？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">理论</div>
          <div class="card-answer-wrapper">
            <div class="card-answer">根据文档中的图示，一个完整的JavaScript实现由三个部分组成：核心（ECMAScript）、文档对象模型（DOM）和浏览器对象模型（BOM）。</div>
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          <div class="card-source">来源: Javascript vs Java</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">特性</div>
          <div class="card-question">JavaScript的基本数据类型有哪些？它在处理数字类型时有什么特点？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">特性</div>
          <div class="card-answer-wrapper">
            <div class="card-answer">文档中列举的基本数据类型包括：Number, String, Boolean, undefined, Null。JavaScript只有一种数字类型，数字可以带小数点也可以不带。</div>
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          <div class="card-source">来源: 基本数据类型</div>
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        <div class="card-face card-front">
          <div class="card-category">机制</div>
          <div class="card-question">在JavaScript中，哪些值在进行逻辑判断时会被视为`false`？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">机制</div>
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            <div class="card-answer">在JavaScript中，除了`false`本身，以下值也被视为`false`：空字符串“”、`null`、`undefined`、数字`0`和`NaN`。</div>
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          <div class="card-source">来源: typeof</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
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        <div class="card-face card-front">
          <div class="card-category">机制</div>
          <div class="card-question">对JavaScript数组中的元素使用 `delete` 操作符会产生什么效果？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">机制</div>
          <div class="card-answer-wrapper">
            <div class="card-answer">使用 `delete` 操作符删除数组元素时，该元素位置会留空，但数组的长度不会发生变化。</div>
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          <div class="card-source">来源: 数组</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">特性</div>
          <div class="card-question">JavaScript中的函数是否可以被当作数据处理？请根据文档举例说明。</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">特性</div>
          <div class="card-answer-wrapper">
            <div class="card-answer">是的，函数在JavaScript中也是一种数据。文档中举例说明可以将一个函数赋值给一个变量，例如：`var add = function(a,b,c){ return a+b+c; }`。</div>
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          <div class="card-source">来源: 函数也是数据</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">技术</div>
          <div class="card-question">JavaScript的预定义函数 `eval()` 的作用是什么？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">技术</div>
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            <div class="card-answer">`eval()`函数会将其接收到的字符串输入当作JavaScript代码来执行。</div>
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          <div class="card-source">来源: 系统提供的预定义函数</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
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        <div class="card-face card-front">
          <div class="card-category">历史</div>
          <div class="card-question">为了统一不同浏览器对JavaScript的实现，最终形成了哪个统一标准？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">历史</div>
          <div class="card-answer-wrapper">
            <div class="card-answer">在Netscape和Microsoft的浏览器大战后，为了统一标准，最终形成了ECMAScript。</div>
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          <div class="card-source">来源: 了解Javascript的历史</div>
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